Control mechanism for trucks



Nov. 16, 1954 M. LEHMANN CONTROL MECHANISM FOR TRUCKS 5 Sheets-Sheet 1Original Filed Sept. 30, 1948 I N V EN TOR. M4)! 1 H/wz/v/v ,4 TERA 7Nov. 16, 1954 M. LEHMANN CONTROL MECHANISM FOR TRUCKS 5 Sheets-Sheet 2Original Filed Sept. 30, 1948 INVENTOR.

MAX [El- MANN .4rraelv'y M. LEHMANN 2,694,460

CONTROL MECHANISM FOR TRUCKS Original Filed Sept. 30, 1948 5Sheets-Sheet 3 l N I 0E @543 m m m un; m M m Nov. 16, 1954 5Sheets-Sheet 4 v INVENTOR. MAX LEIH MANN B ATTORNEY? M. LEHMANN CONTROLMECHANISM FOR TRUCKS Nov. 16, 1954 Original Filed Sept. 30, 19482,694,460 CONTROL MECHANISM FOR' TRUCKS Max Lehmann, EastCleveland,.Ohio, assignor totThe Baker-Raulang Company, Cleveland, Ohio,a corporation of Ohio Original application September 30, 1948, SerialNo. 51,979 now Patent No. 2,689,662, dated-September 21, 1954. Dividedand this application 'August9, 1950, Serial No. 178,540

11 Claims.- (Cl. 180-77) This invention relates to a powerdriven truckadvantageously operable in mines, that is, driven into :and through themain entry, panel entry. andblock roomof a mine. The truck isparticularly adapted for handling and positioning timber and bars forthe mine roofs where excavations in the mine have been completed, :thetruck having a boom for raising the timbers and maintaining them-inaccurate elevated relation to the mine roof while props therefor arebeing cut and placed in position. The chassis of the truck .isconstructed to supportthe truck platform at a low level. 'The powersupply and power mechanisms are mounted below the .platform, and as theboom may be-disposed in a horizontal position during truck travel, theoverall height of thetruck is reduced, so that it may be driven throughmine1areas and the boom operated where overhead conditions are limited.

Due to the fact that the truck is employed under conditions requiring itto be driven long distances through narrow passageways, provision ismade for driving it forwardly and rearwardly in a ready manner by anarrangement ofcontrol elements, whereby the driver. can always face thedirection of travel. Such-arrangement not only enables faster travel ofthe truck but eliminates unforeseen dangers to life and other accidents.

One object of the invention is to providein a power driven vehicleimproved mechanically-operated.-mechanism for controllingtranslatorymovement of the vehicle and which is mounted at a controlstation andassociated with spaced opposed supports for a driver, wherebythe latter may face the direction in which the truck-is'being driven.

Another object of the invention is to provide in a truck having a motorfor driving it and a brake,.duplictae operating devices for controllingthe operation of the motor and brake, respectively, positioned at acontrol station, corresponding operating devicesfori the motor and brakebeing related to the respective seats for the driver, whereby thelatter, when driving the truck in either direction can face thedirection in which it is travelling.

A truck of this type, when used in a mine, must often be driven longdistances to and from the location where work and installaitons are tobe made and as thetru'ck cannot be turned around it has to be backed toa'place of a parking or to another location; accordingly, another objectof the invention is to provide improved dualoperating devices fordriving, braking, parking of the truck disposed in a control station atone side and-below.the level of the platform, whereby .the driver may.face forwardly or backwardly dependent upon "the direction the truck isto be driven.

Another object of the invention. is to. provide an improved truck havinga driving mechanism and-a brake, spaced seats for a driver and separate,side-by-sideconnected-together dual control devices between the seatsforoperating the drivingmechanism and the brake.

Other objects of the invention will be apparent to those skilled in theart to which my invention relates'from the following description takenin connection with the accompanying drawings, wherein Fig. 1 is a planview of atruck embodying myinvention with the outer. portion ofthe boombeingomitted;

Fig. 2 is a perspective view (somewhat diagrammatic) of the controlstation for controlling theoperationof the truck;

United States Patent hollow bosses 23 Fig. 3 is a fragmentary plan viewof the control station,

.enlarged;

.Fig. 4 is a fragmentary elevation on'the line 44 of Fig. 3;

Fig; 5 is an enlarged section on the line 5-5 of Fig. 4; Fig.6 is asectionon theline 6-6 of Fig. 3; Fig. '7 is a fragmentary sectionsubstantially on the .line -7--7- of Fig. 3, enlarged and parts beingbroken away;

2 Fig. 8. is a view on the line 8-8 of Fig. 7, partsbeing broken away.

..'Fig. 9 is a section on the line 99 of Fig. 7; and I Fig. 10 is asection on the line 1010 of Fig. 5;-and Fig. 11. is a fragmentary planview showing a modified form of. construction.

Referring to the drawings, the invention is illustrated .as.embodied ina truck having a chassis, generally designated by, the reference numeral1, supported on a pair of steerable .front wheels 2 and rear tractionwheels 3. The front wheels 2 may be connetced to the chassis 1 andsteerable by the mechanism disclosed and described in detail in mycopending application Serial No. 51,979,

ffiledSeptember 30, 1948, the particular structure of the steeringmechanism :not forming a part of the present invention except ashereinafter set forth. At one side of the chassis 1 and intermediate thefront and rear .wheels,.a control station A is provided havingassociated therewith or therein (a) various devices and levers, theopertaion of which, through valves and other devices, effectdriving andbraking of the truck and operation of a boom 4 supported on the forwardpart of the chassis 1, and (b) front and rear seats 5 and 6,respectively,

'for. the driver, the control station including a floor 7 locatedadjacent the underside of the chassis 1 and connected. at its oppositeends to the lower ends of spaced 5 and 6 so that it is operable by thedriver when occupying either of the seats. Power means comprising anelectric motor 12, in the illustrated embodiment, for driving thetraction wheels 3 is located in. a compartment 13 adjacent'the controlstation A. The-particular mechanism of the power meansinterconnectingthe motor 10 and theitraction wheels 3 forms no part ofthe present invention and,.therefore, will not be described in detail.The powermeans includes a battery 14 adapted to be connected to themotor 10 by control means to be described in detail hereinafter.

' The boom 4 is-preferably mounted by suitable mechanism, not shown, forbodily movement endwise, movement about a vertical axis on the chassis 1and for swingable movement upwardly and downwardly and is provided atits outer end with a cradle, not shown. The operation of the boom iscontrolled from station A by devices indicated at 15.

As already set forth, provision is made in the control "station A forthe driver, when heis occupying eitherseat 5, 6, to control'theoperation of the traction motor 12 and the braking of the trucktraveland stoppage thereof.

.Themeans for controlling the operation of the motor 12 and the brakingof the truck include elements adapted to be manually engaged by the.driver and similarly related 'tothe; seats; 5, 6, :so that operationand control of the "truck is facilitated when the driver is ineither'seat.

The control meansfor the traction motor 12 comprises the following: 20,21, indicate foot pedals each provided atits lower end with a knuckle 22fitting between formed integrally with a base 24 and pivotally connectedby a pin .25 extending through the knuckle and bosses. The bosses 23 aresuitably fixedto the'floor'7. The pedal 20 is adapted to be engaged byhe occupies seat 5, 'is adapted to be engaged bythe left foot ofthedriver' when he occupies the seat 6. The

pedals 20, 21, are connected together by a link 26, one

end of which (that end remote from the pedal 21) is pivotally connectedto the outer end of a link 27. The opposite end of the link 27 ispivotally connected to an arm 29 having a hub 30 which is suitably keyedas indicated at 31 to the outer end of a shaft 32. The shaft 32 extendsthrough and rotates in a bearing 33 mounted in a wall 35 which isrigidly connected to and depends from the seat 6. The shaft 32 isoperatively connected to a controller which controls the operation ofthe traction motor 12. The inner end of the shaft 32 is provided with asegmental gear 38 integrally formed with a circular clamp 39 whichencircles and fixes the gear 38 to the shaft 32. The segmental gear isin mesh with a pinion 40, the latter in turn being suitably keyed to acontroller shaft 41 extending outwardly of a motor controller casing 42,as indicated at 43. The motor controller casing 42 houses a controllerfor controlling the application of power from the battery 14 to thetraction motor 12 and is supported above the flooring 7 adjacent to thewall 35. The controller shaft 41 extends outwardly of the casing 42 andhas the pinion 40 secured to the outer end thereof. It will be seen thatthe controller within the controller casing 42 and the shaft 32operativelyv connected to the controller by shaft 41 and pinion 40constitute a means for controlling the application of power to the motor12, the means being actuated by the depression of pedals 20, 21operatively connected to the shaft 32.

The connection between the link 26 and each pedal 20, 21 consists of aheaded pin 44 extending through an opening formed in the link and ahollow boss 45 welded to the under side of the adjacent pedal. Springmeans, indicated as an entirety at 46, preferably connected to the arm29, operates to normally maintain the latter in neutral position and,through the link 27 and link 26, to support the pedals 20, 21 in normalor inoperative position. As shown, the link 26 and arm 29 are normallydisposed horizontally and in parallel relation and the link 26 is movedsubstantially endwise when foot pressure is applied to either pedal 20,21, to swing it about its pivot 25, whereas the link 27 is normallydisposed at a substantially 30 angle to the arm 29'and link 26. In thisarrangement it will be observed that (a) when the driver is occupyingseat 6 and pushes pedal 21 clockwise (as viewed in Fig. 6), arm 29 willbe swung counter-clockwise, the effect of which is to rotate thecontroller shaft 41 clockwise and drive the motor 12 in a direction topropel the truck in the forward direction; and (I2) when the driveroccupies the seat and pushes pedal 20 counter-clockwise, the arm 29 willbe swung clockwise, so that the controller shaft 41 will be rotated inthe opposite direction and propel the truck rearwardly. By preferencethe link 27 consists of two endwise related sections 47, 48. The outerends of the sections 47, 48, are bifurcated and pivotally connected tothe adjacent end of the link 26 at 50 and outer end of the arm 29 at 51,respectively, whereas the inner end of the section 47 is formed with aninwardly extending screw threaded opening to adjustably receive thethreaded shank on the inner end of the section 48, so that when the arm29 is in neutral position, both pedals 20, 21, will be disposed indiverging relation and in the same angular relation to the flooring 7.

The spring biasing means 46 preferably comprises a projection or fixedstop 52 on the outer side of the wall 35 disposed in a horizontal planethrough the arm 29 when the latter is in neutral or normal position, atensioning element or movable stop 53 extending laterally inwardly fromthe arm 29 to the right of the projection 52 as viewed in Fig. 5, and apair of springs 55, 56 telescoped over the outer wall of the bearing 33.The springs 55, 56 are located side-by-side on the outer wall of bearing33 and with the intermediate portion of the springs being coiled aboutthe bearing wall, the opposite ends 57, 58 of each spring 55, 56extending outwardly over oppositely disposed portions of the projection52 and tensioning element 53. The extended end portions 57, 58, of thesprings leading from the upper and lower sides of the wall of thebearing 33 are bent in opposite directions and engage the lower andupper sides, respectively, of the projection 52 and outwardly of thelatter the end portions 57, 58, are seated in notches 60 formed in theupper and lower edges of the tensioning element 53. I

In the arrangement shown and above described, it will be observed thatwhen the arm 29 is operated in either direction, the tensioning element53 will move and flex theendportions 57 of the springs 55, 56 againstthe projection 52 in opposition to the tension of the wires, whereas theother end portions of the springs will be held by the projection 52.Accordingly, with the stored energy in the end portions of the twosprings, upon release of pressure on the operated foot pedal, thesprings 55, 56 will return the arm 29, links 27, 26 and pedals 20, 21 tonormal position.

Limit means, indicated as an entirety at 62, are provided for limitingthe swinging movement of the pedals 20, 21, when either one is operated,so as to prevent angular movement of the controller drum beyond apredetermined position. The means 62 are preferably provided between thelink 26 and an upstanding wall 63 fixed to the floor 7 and disposedparallel to the link 26. A pair of spaced abutments or stops 65, 66 arefixed to and project laterally from the face of the wall 63 between thepedals 20, 21. An abutment or block 67 is welded to and depends from thelink 26 and is disposed intermediate and is substantially equally spacedfrom the stops 65, 66, when the pedals are in normal position. The block67 may engage either stop dependent on the direction of movement of thelink 26. In order to regulate the movement of the controller drum, theopposite ends of the block 67 are provided with adjustable devicesconsisting of screw threaded rods 68 threaded into threaded openingsformed in the ends of the block 67 and projecting therefrom. Each of therods is locked in adjusted position by a nut 69. By loosening the nuts,the rods 68 can be turned, the effect of which is to adjust them endwisefor engagement with the stops, and thus regulate the movement of thepedals by the driver. It will be observed that where error occurs inpositioning the block 67 on the link 26, the rods 68 may be adjusteddifferent distances to compensate for such error.

The means for applying the brakes comprise the following: 70, 71,indicate pedals mounted on the floor 7 similarly to the pedals 20, 21,and inclined at the same angle and preferably each in transversealinement to one of the latter pedals. In this arrangement, when thedriver is occupying the seat 6, he uses his right foot to engage andswing the pedal 71 in a counterclockwise direction, as viewed in Fig. 2,to brake the movement of the truck and when the driver is occupying theseat 5, he uses his left foot to engage and swing the pedal 70 in aclockwise direction, as viewed in Fig. 2, to brake the travel of thetrack.

From the foregoing description it will be observed that the steeringwheel 10 is disposed substantially midway the seats 5, 6, and that eachset of pedals 20, 70 or 21, 71 bears the same relation to the seatremote therefrom, so that the operation of the devices to control thedriving of the truck is facilitated when the driver is in either seat 5or seat 6. Each pedal 70, 71 is pivotally connected to the outer end ofa link 72. The inner ends of the links 72 are pivotally connected to arocker member or lever 73 at opposite sides of a shaft 81, whichprovides a fulcrum for the lever 73, so that when either pedal 70 orpedal 71 is operated to apply a brake 76, which is shown in Fig. l, thelever 73 is swung or rocked in the same direction. The lever 73 servesas one of the operating connections between the links 72 and the brake76 to operate the latter and to set the brake in parking position and torelease the brake for operation as later set forth. By preference eachlink 72 consists of endwise related sections 77, 78. The outer endportion of each section 77, 78 is offset and bifurcated and pivotallyconnected to the lever 73 (see Fig. 8), whereas the inner end of eachsection is formed with an inwardly extending screw threaded opening toadjustably receive the inner threaded end portion of the adjacentsection 78, whereby the pedals 70, 71 may be disposed at the sameinclination relative to the floor 7. The lever 73 is provided at oneside with a collar 79 which is fixed to a shaft 81 by a pin 80. Theshaft 81 is mounted in spaced standards 82, 83. Between the standards82, 83, the shaft 81 is provided with a member or collar 84 which isfixed to the shaft 81 by a pin 85 and has at one side a segmental wall86, one face of which is recessed to form converging walls 87, 88,connected at their inner ends and forming a seat for a roller element90. The walls 87, 88 operate as cams and terminate in rests 91, 92, thepurpose of which will later be set forth. The roller 90 is mounted,preferably by anti-friction bearings, on a stud shaft 93 the wheels 3.mounted on the floor 1115, both pedals being connected mounted on oneend of a rocker 94 and'is adapted'to ride one of the cams 87, 88 uponrotation of the shaft 81. The rocker 94 is mounted on a shaft 95suitably supported on the floor 7. 'The opposite end of the rocker 94 isconnected to one end of a cable 96 engaging pulleys 97, 98, and con-'the lever 73 to the position shown in dottedlines at a (Fig. '7) androtate shaft 81; in this operation the wall 86 revolves with the shaft81 in one direction causing the roller 90 to ride the adjacent wall orcam 87 or-88, the effect of which is to rock the rocker 94 and apply thebrake'76. By operating the operated pedal 70 or 71 to swing the lever 73to the position shown in dotted lines at b in Fig. 7, the roller 90rides onto the adjacent rest 91 which locks the lever 73 againstmovement under the influence of the brake spring 100, thereby settingthe brake 76 'so as to park the truck. It will be observed that when thepedals are operated to the parking position, as indicated at b in Fig.7, the pedals 20, 21, are inoperative; further movement of either pedalin the brake applying direction is ineffective and the spring 100 isineffective so long as the rest 91 is disposed in the path of swingingmovement of the roller 90. For the purpose of resettingthe cam 87 andrepositioning the pedals 70, 71 in normal position, the lever 73 isprovided with an extension 102 having a knob at its upper end adapted tobe grasped by the driver, whereby he can swing the lever 73 back tonormal position, the effect of which is to rotate the collar 84 and movethe rest 91 out of engagement with the roller 90, and thus permit thebrake spring 100 to release the brake 76 and return the pedals.

It will be observed that both walls 68, 87 may serve as cams so that ifthe lever 73 is operated clockwise for any reason, the rocker 94 will berocked and the brake 76 applied.

Fig. 11 shows a modified form of construction, wherein seats for thedriver in the control station A are not employed, but the driver indriving the truck forwardly sits on the floor 105 with his back bracedagainst the adjacent wall 9, and in driving the truck rearwardly thedriver sits on the floor 105 with his back braced against the verticalmember 8.

106 indicates a lever having at one end a handle disposed centrally ofthe station and adapted to be operated .by the driver when he is ineither driving position. The opposite end of the lever 106 is connectedby linkagewith a suitable controller for controlling current from asuitable power supply on the chassis to themotor 12 which drives 107,108, indicate foot pedals suitably together and to one end of a rocker110. The opposite end of the rocker 110 is connected by a cable 111 tothe brake 76 in the same manner as the first-described embodiment. Whenthe driver is in forward driving position he operates pedal 1'08 withhis left foot to effect braking and when the driver is in rearwarddriving position he operates the pedal 107 with his right foot to effectbraking.

This application is a division of my application filed September 30,1948, Ser. No. 51,979, now Patent No. 2,689,662, dated September 21,1954.

To those skilled in the art to which my invention relates many changesin construction and widely differing embodiments and applications of theinvention will suggest themselves without departing from the spirit andscope of the invention. My disclosures and the description herein arepurely illustrative and are not intended to be in any sense limiting.

What I claim is:

1. In a truck having a chassis mounted on traction and steerable wheels,power supply means on said chassis, driving means for said tractionwheels including a motor to be driven from said power supply means,controlling means on said chassis for controlling the application ofsaid power supply means to said motor for operating the latter, acontrol station comprising a flooring supported by said chassis andfront and rear means above said flooring providing seats for a driver,an element at said station disposed substantially midway between saidseat means operatively connected to said steering wheels for operatingthe latter, a pair of pedals comprising forward and rearward pedalspivotally mounted on said flooring, each pedal being adapted to beoperated when the driver occupies one of said seats, a-link pivotallyconnectedto said pedals, means connecting said link tosaidcontrollingmeans for operating the. latter, and stop means for limitingthe movement of said link comprising spaced first abutment means andsecond abutment-meansintermediate-said spaced firstabutment meansadaptedto engageand cooperate with said spaced first-abutment means tolimit the movement of said-link,- one:of-said abutment'rneans beingsupported'on said link:and the=other of said. abutment means beingsupported on said chassis.

'2. In a truck,-the combination'of a chassis mounted on traction andsteerablewheels, amotor mounted onsaid chassis for driving saidtractienwheels; a power supply on said chassis for said motor including arotatable shaft for operatively connecting said power supplytosaidmotor, an arm fixed to said shaft for rotating-the latter in eitherdirection, a control station consisting of a flooring on-said chassisand oppositely facing front-'and' rear-seats adapted to be selectivelyoccupied by adriven a pair of .alined pedals pivotally mounted on saidflooring between said seats, connections between said pedals andsaidarmfor operating the latter in either directionupon movement of saidpedals, each of said pedals being adapted to be'operated by thedriverwhen the latter occupies a corresponding one of saidseats, a stopfixedly m'ounted on said chassis and disposed at one side and in theplane of said arm when the latter is in its neutral position;astop onsaid arm outwardly of said first mentioned stop, a spring coiled aroundsaid shaft, each end portion of said spring being extended and offsetfrom the other end portion, said end portions engaging'oppositelydisposed sides of said stops when said :armis 'in'its neutral position.and cooperating with each other to maintain said arm inits neutralposition, one end portion of said spring. being movable with said stopon said arm when said-arm is moved in one directionwith the other endportion of said spring being held againstirnovement 'bysaidfirst-mentioned stop,-whereby said spring is put under tension.

3. In a truck,the combination ofla chassis mounted" on pairs of tractionand steerable wheels, a control station on said chassis having aflooring and opposed supporting means for a driver, a power operatedmeans on said chassis-for driving said traction'wheels, a brake forbraking said traction wheels including a movablemember for actuating thebrake, a pair of pedals comprising forward and rearward pedals' mountedon said'fiooring between said driver supporting means; and mechanicalconnections between said pedals and said movable-member for moving thelatter to actuate said brake upon the-movement of either one of saidpedals, said mechanical' connections comprising a rockshaft-mountedon'said-fiooringsintermediate said pedals'for rotation about its axis,afirst member fixed tosaid shaft, links connecting said pedals to saidfirst member at opposite sides above and below the axis of said shaft torotate the-latter when eitherpedal is-operated, a second member fixed tosaid shaft saidsecond member having on one side thereof a pair of camsextending outwardly therefrom, an element engaging said cams andoperatively connected to said movable member, said elementriding'one'ofsaid cams to move said movable member to operate 'said'brake when' either. of said pedals is operated 'to-rock'said cams, andspring means operatively connected between said movable member and saidchassis for urging'said movable member and said second member throughsaid element to a normal brake-released position when said element is inengagement with either of said cams and for yieldably urging saidelement into engagement with said second member.

4. A truck as claimed in claim 3 wherein the outer end of each of saidcams terminates in a surface to be engaged by said element, said surfacebeing in a plane normal to the axis of said rockshaft and opposing theforce of said spring means tending to return said element and saidsecond member to a normal brake-released position whereby said brake isset in parked position, and a handle connected to said first member formoving said surface out of engagement with said element.

5. A truck for translation in a mine and like areas and having incombination, a chassis, pairs of traction and steerable wheels forsupporting the opposite ends of said chassis, a control station providedwith a floor and opposed seats for a driver, a power means on saidchassis for driving said traction wheels, a brake for braking saidtraction wheels, including a member movable to operate the brake, aspring means operatively connected between said chassis and said memberurging said member to a brake-released position, a pair of-alined pedalspivotally mounted on said floor for movement about parallel axes, a rockshaft mounted on said floor between and parallel to the pivot axes ofsaid pedals, a lever fixedly connected intermediate its ends to saidrock shaft, links connecting said pedals to said lever at opposite sidesabove and below the axis of said rock shaft, and means interconnectingsaid lever and said member including cam means connected to said rockshaft and actuated by the rocking of said rock shaft on the operation ofeither pedal and linkages interconnecting said cam means and said memberto operate said brake upon the actuation of said cam means by therocking of said rock shaft.

6. In a truck operable in excavated areas having, in combination, achassis supported at its opposite ends on pairs of traction andsteerable wheels, a control station at one side of said chassiscomprising a flooring and seats for a driver which are disposed at theopposite ends of said flooring and supported in forwardly and rearwardlyfacing directions, power means on said chassis for driving said tractionwheels, rotatable control means for controlling the operation of saidpower means, a brake for said traction wheels, first and second pairs offorwardly and rearwardly alined pedals pivotally mounted in side by siderelation on said flooring between said seats, the pivot for each pedalof one pair and the adjacent pedal of the other pair being equallyspaced from the seat remote thereto, a link pivotally connected to thefirst pair of pedals and operatively connected to said rotatable controlmeans for operating the latter upon movement of the pedals, a rockermember mounted on said chassis, linkages between the pedals of thesecond pair of pedals connected to said rocker member at opposite sidesof and above and below the fulcrum therefor, whereby operation of eitherpedal of said second pair of pedals operates said rocker member in onedirection, and a cam operated device connected to said rocker member foractuation upon movement thereof and operatively connected to said brakefor operating the latter when said rocker member is operated in eitherdirection.

7. In a truck having, in combination, a chassis supported on pairs oftraction and steerable wheels, an electric motor on said chassis fordriving said traction wheels, a

power supply on said chassis for said motor, circuit means 1 connectingsaid power supply and said motor and including a controller, forwardlyand rearwardly facing seats for a driver on said chassis, swingable armconnected to said controller for operating said controller in oppositedirections, spring means connected between said arm and said chassis forresisting swinging movement of said arm in either direction from aneutral position, a pair of alined spaced pedals pivotally mounted onsaid chassis between said seats, an endwise movable link pivotallyconnected to said pedals and disposed substantially parallel and inoverlapping relation to said arm and a connecting link pivotallyconnected at its opposite ends to the overlapping end of said endwisemovable link and the outer end of said arm respectively, whereby endwisemovement of said link will swing said arm in either direction dependenton the direction of movement of said link.

8. A truck as claimed in claim 7 wherein said connecting link consistsof related sections, the end portions of which are endwise adjustablyconnected together.

9. A truck as claimed in claim 8 having stop means for limiting movementof said pedals comprising spaced first abutment means and secondabutment means intermediate said spaced first abutment means adapted toengage and cooperate with said spaced first abutment means to limit themovement of said pedals in either direction, one of said abutment meansbeing connected to said endwise movable link and the other of saidabutment means being supported by said chassis.

10. A truck for translation in a mine or like areas having, incombination, a chassis, pairs of traction and steerable wheels forsupporting said chassis, power means on said chassis for driving saidtraction wheels, a brake including a movable member for actuating saidbrake, a spring connected to said movable member and said chassis forbiasing said movable member into a brake-released position, a pair ofalined pedals pivotally mounted on said chassis, a rockshaft rotatablymounted on said chassis, a lever fixedly connected intermediate its endsto said shaft, links connecting said pedals to said lever at oppositesides and above and below the axis of said shaft, a cam member fixed tosaid shaft and having a cam with reversely related cam surfacesextending outwardly therefrom, a movable element normally in engagementwith said cam and adapted to ride either of said cam surfaces when thecam is rocked by the operation of one of said pedals, linking meansinterconnecting said movable element and said movable member for movingthe latter in opposition to said spring when said movable element rideseither of said cam surfaces, said spring acting through said linkingmeans and said movable element to urge said cam member to a normal brakereleased position when said movable element is in engagement with eitherof said cam surfaces and to urge said movable element into engagementwith said cam member.

11. A truck as claimed in claim 10 wherein each of said cam surfacesterminates in a surface adapted to be engaged by said movable elementwhen either of said pedals is operated to a predetermined position, thelastsaid surface being substantially normal to the force applied theretoby said movable element when in engagement therewith and due to theaction of said spring whereby the brake is set in parked position.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,212,616 Fageol Ian. 16, 1917 1,384,073 Lee July 12, 19211,681,319 Bartlett Aug. 21, 1928 2,209,177 Stoltz July 23, 19402,298,448 Arentzen Oct. 13, 1942 2,301,144 Russell Nov. 3, 19422,325,731 Arentzen et a1. Aug. 3, 1943 2,358,236 Lee Sept. 12, 19442,360,282 Russell Oct. 10, 1944 2,378,892 Arentzen June 26, 1945 FOREIGNPATENTS Number Country Date 148,365 Great Britain Nov. 25, 1920

